Origin of the names

‘Lepto’ comes from the Greek word for ‘thin’; ‘pteris’ is the Greek word for ‘fern’; ‘hymenophylloides’ means ‘resembling Hymenophyllum’, which is the name of the genus of the filmy ferns. These will be the subject of a future article. ‘Heru’ in Te Reo means ‘comb’ – please refer to the Uses section below.

Distribution and habitat

This endemic fern grows on Te Ika a Māui/North and Te Wai Pounamu/South islands, and on Rakiura/Stewart and Rekohu/Chatham islands. Heruheru is common throughout the country, although it is more common in northern areas. Look for it in lowland to montane forests up to 1000 m, on damp banks along tracks and creeks, and also on exposed sites on open ridges.

Rhizome

Heruheru’s erect, woody, trunk/rhizome can be 50 cm tall, and occasionally up to 100 cm tall.

Growth habit

The stipes/stalks of the fronds are 15–50 cm long, pale brown, with scattered hairs, and ear-like lobes at the base. The dark green fronds are finely divided, flat, and almost triangular, 20-100 cm long x 15-35 cm wide, and have scattered hairs. The segments/pinnae are all in the same plane.

The fronds of heruheru, and its relative, the striking Leptopteris superba / Prince of Wales’ feathers,^footnote^', are mostly one cell thick and translucent, just like the fronds of filmy ferns, with which they can be confused when immature. Place your hand under a heruheru frond, or the frond of one of the filmy ferns, then move your hand from side to side. Shadow-like, you will see your hand moving on the other side of the frond.

Reproduction

The sporangia, the capsules which contain spores, are scattered on the undersides of the fronds, not grouped in discrete sori, as in the ferns described so far in The Tramper. This distinctive feature of the Leptopteris genus led to it being classified as a member of an ancient family of ferns, the Osmundaceae.

Uses

Māori used the hard stipes/stalks of the fronds as teeth for heru/hair combs. (Best, 1899, 1908). No uses of heruheru for rongoā or food have been recorded in NZ. Have you heard of any?
Heruheru was exported to England in the 1800s, together with several other species of ferns, during a ‘fern craze’ there.

Where to look for heruheru

Look for this widespread fern whenever you go tramping in Wellington city’s reserves, and on tramps elsewhere up to 1,000 m above sea level. Its delicate fronds are an eye-catching feature in many bush areas.